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Exposure of tumor-associated macrophages to apoptotic MCF-7 cells promotes breast cancer growth and metastasis.

Zhou N, Zhang Y, Zhang X, Lei Z, Hu R, Li H, Mao Y, Wang X, Irwin DM, Niu G, Tan H - Int J Mol Sci (2015)

Bottom Line: Tumor-associated macrophages (TAMs) have been found to be associated with the progression and metastasis of breast cancer.Macrophages co-cultured with apoptotic MCF-7 had increased tumor growth and metastatic ability in a nude mouse transplantation assay.During this process, macrophages secreted increased amounts of interleukin 6 (IL-6) leading to increased phosphorylation of signal transducers and activators of transcription 3 (STAT3), which likely explains the increased transcription of STAT3 target genes such as TGF-β1 and HIF-1α.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, Peking University, Health Science Center, Beijing 100191, China. zhouna@bjmu.edu.cn.

ABSTRACT
Tumor-associated macrophages (TAMs) have been found to be associated with the progression and metastasis of breast cancer. To clarify the mechanisms underlying the crosstalk between TAMs and cancer stem cells (CSCs) in breast cancer recurrence and metastasis, we used a co-culture model of macrophages and apoptotic human breast cancer cell line MCF-7 cells to investigate the effects of TAMs on MCF-7 in vitro and in vivo. Macrophages co-cultured with apoptotic MCF-7 had increased tumor growth and metastatic ability in a nude mouse transplantation assay. The macrophages exposed to apoptotic cells also induce an increase in the proportion of CD44+/CD24- cancer stem-like cells, as well as their proliferative ability accompanied with an increase in mucin1 (MUC1) expression. During this process, macrophages secreted increased amounts of interleukin 6 (IL-6) leading to increased phosphorylation of signal transducers and activators of transcription 3 (STAT3), which likely explains the increased transcription of STAT3 target genes such as TGF-β1 and HIF-1α. Our results indicate that when cancer cells endure chemotherapy induced apoptosis, macrophages in their microenvironment can then activate cancer stem cells to promote cancer growth and metastasis by secreting IL-6, which activates STAT3 phosphorylation to regulate the transcription of its downstream target genes.

No MeSH data available.


Related in: MedlinePlus

Analysis of CD44+/CD24− subpopulations in MCF-7 cells. (A) Analysis of the apoptotic effect of H2O2 on MCF-7 cells. Percentage of apoptotic cells is the sum of the events in the upper right and lower right quadrants; (B) Flow cytometry analysis and quantification of the size of the CD44+/CD24− subpopulation of MCF-7 cells treated with different types of conditioned media. Results are typical of three independent experiments. Data represent means ± S.E. (n = 3). *p < 0.05, ***p < 0.001 (Mac: conditioned media from macrophages alone; Apo: conditioned media from apoptotic MCF-7 cells alone; CoM: conditioned media from a co-culture of macrophages and MCF-7 cells; CoA: conditioned media from a co-culture of macrophages and apoptotic MCF-7 cells).
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ijms-16-11966-f001: Analysis of CD44+/CD24− subpopulations in MCF-7 cells. (A) Analysis of the apoptotic effect of H2O2 on MCF-7 cells. Percentage of apoptotic cells is the sum of the events in the upper right and lower right quadrants; (B) Flow cytometry analysis and quantification of the size of the CD44+/CD24− subpopulation of MCF-7 cells treated with different types of conditioned media. Results are typical of three independent experiments. Data represent means ± S.E. (n = 3). *p < 0.05, ***p < 0.001 (Mac: conditioned media from macrophages alone; Apo: conditioned media from apoptotic MCF-7 cells alone; CoM: conditioned media from a co-culture of macrophages and MCF-7 cells; CoA: conditioned media from a co-culture of macrophages and apoptotic MCF-7 cells).

Mentions: To mimic the breast cancer microenvironment treated with chemotherapy, we cultured MCF-7 with several different types of macrophage-conditioned media, media conditioned by only macrophages, by macrophages co-cultured with MCF-7 cells, and macrophages co-cultured with apoptotic MCF-7 cells. The co-culture with apoptotic cells is a model of the chemotherapy induced microenvironment. We used H2O2, which is toxic to cells and induces hypoxia [15], to induce apoptosis in MCF-7 cells. Levels of apoptosis induced by H2O2 were examined using flow cytometric analysis after PI-Annexin V co-staining of the cells. H2O2 induces an apoptotic effect on the human MCF-7 cell line, with 0.3 mM H2O2 generating nearly 100% apoptosis in these cells (Figure 1A). All further experiments used 0.3 mM H2O2 to generate apoptotic MCF-7 cells.


Exposure of tumor-associated macrophages to apoptotic MCF-7 cells promotes breast cancer growth and metastasis.

Zhou N, Zhang Y, Zhang X, Lei Z, Hu R, Li H, Mao Y, Wang X, Irwin DM, Niu G, Tan H - Int J Mol Sci (2015)

Analysis of CD44+/CD24− subpopulations in MCF-7 cells. (A) Analysis of the apoptotic effect of H2O2 on MCF-7 cells. Percentage of apoptotic cells is the sum of the events in the upper right and lower right quadrants; (B) Flow cytometry analysis and quantification of the size of the CD44+/CD24− subpopulation of MCF-7 cells treated with different types of conditioned media. Results are typical of three independent experiments. Data represent means ± S.E. (n = 3). *p < 0.05, ***p < 0.001 (Mac: conditioned media from macrophages alone; Apo: conditioned media from apoptotic MCF-7 cells alone; CoM: conditioned media from a co-culture of macrophages and MCF-7 cells; CoA: conditioned media from a co-culture of macrophages and apoptotic MCF-7 cells).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4490423&req=5

ijms-16-11966-f001: Analysis of CD44+/CD24− subpopulations in MCF-7 cells. (A) Analysis of the apoptotic effect of H2O2 on MCF-7 cells. Percentage of apoptotic cells is the sum of the events in the upper right and lower right quadrants; (B) Flow cytometry analysis and quantification of the size of the CD44+/CD24− subpopulation of MCF-7 cells treated with different types of conditioned media. Results are typical of three independent experiments. Data represent means ± S.E. (n = 3). *p < 0.05, ***p < 0.001 (Mac: conditioned media from macrophages alone; Apo: conditioned media from apoptotic MCF-7 cells alone; CoM: conditioned media from a co-culture of macrophages and MCF-7 cells; CoA: conditioned media from a co-culture of macrophages and apoptotic MCF-7 cells).
Mentions: To mimic the breast cancer microenvironment treated with chemotherapy, we cultured MCF-7 with several different types of macrophage-conditioned media, media conditioned by only macrophages, by macrophages co-cultured with MCF-7 cells, and macrophages co-cultured with apoptotic MCF-7 cells. The co-culture with apoptotic cells is a model of the chemotherapy induced microenvironment. We used H2O2, which is toxic to cells and induces hypoxia [15], to induce apoptosis in MCF-7 cells. Levels of apoptosis induced by H2O2 were examined using flow cytometric analysis after PI-Annexin V co-staining of the cells. H2O2 induces an apoptotic effect on the human MCF-7 cell line, with 0.3 mM H2O2 generating nearly 100% apoptosis in these cells (Figure 1A). All further experiments used 0.3 mM H2O2 to generate apoptotic MCF-7 cells.

Bottom Line: Tumor-associated macrophages (TAMs) have been found to be associated with the progression and metastasis of breast cancer.Macrophages co-cultured with apoptotic MCF-7 had increased tumor growth and metastatic ability in a nude mouse transplantation assay.During this process, macrophages secreted increased amounts of interleukin 6 (IL-6) leading to increased phosphorylation of signal transducers and activators of transcription 3 (STAT3), which likely explains the increased transcription of STAT3 target genes such as TGF-β1 and HIF-1α.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, Peking University, Health Science Center, Beijing 100191, China. zhouna@bjmu.edu.cn.

ABSTRACT
Tumor-associated macrophages (TAMs) have been found to be associated with the progression and metastasis of breast cancer. To clarify the mechanisms underlying the crosstalk between TAMs and cancer stem cells (CSCs) in breast cancer recurrence and metastasis, we used a co-culture model of macrophages and apoptotic human breast cancer cell line MCF-7 cells to investigate the effects of TAMs on MCF-7 in vitro and in vivo. Macrophages co-cultured with apoptotic MCF-7 had increased tumor growth and metastatic ability in a nude mouse transplantation assay. The macrophages exposed to apoptotic cells also induce an increase in the proportion of CD44+/CD24- cancer stem-like cells, as well as their proliferative ability accompanied with an increase in mucin1 (MUC1) expression. During this process, macrophages secreted increased amounts of interleukin 6 (IL-6) leading to increased phosphorylation of signal transducers and activators of transcription 3 (STAT3), which likely explains the increased transcription of STAT3 target genes such as TGF-β1 and HIF-1α. Our results indicate that when cancer cells endure chemotherapy induced apoptosis, macrophages in their microenvironment can then activate cancer stem cells to promote cancer growth and metastasis by secreting IL-6, which activates STAT3 phosphorylation to regulate the transcription of its downstream target genes.

No MeSH data available.


Related in: MedlinePlus